Wow...I'm stoked.....  | | 
02-13-2009, 03:08 PM
|  | Still Alive & Well | | Join Date: Dec 2008 Location: 39° 19' 23" N X 74° 36' 30" W
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Quote:
Originally Posted by moleculo   Now you got the HF bug. It's so much fun just stringing some wire up and getting on the air.
Do you have an antenna tuner? If so, you might want to consider replacing that coax with ladder line and just using your 40m dipole on all the bands below it. The losses will be negligable and then you don't have to worry about changing antennas. | Mole...just won a Kenwood AT-130 antenna tuner on eBay, it's the matching unit to this TS-130S. I don't believe it has the capacity for a balanced line feed since the description stated that it has 4 SO-239 connectors for 4 different antenna feeds....
Are you telling me that with a coax feed I won't be able to tune a 40m dipole to work on 20m...or any other band......????
That would suck.....
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02-13-2009, 05:57 PM
| | Senior Member | | Join Date: Sep 2006 Location: Fountain, MI
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you should be able to tune 20m on a 40m antenna that is coax fed. Don't quote me on that, but it should work.
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Allen
CDX015
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015 from Michigan
KD8FXB
Kenwood TS430s Maco 3's, A99, 80-10 balanced wire and a 20m vertical dipole
" LIFE'S A B**CH, DEAL WITH IT" |
02-13-2009, 08:24 PM
|  | Senior Member | | Join Date: Dec 2005 Location: Western Washington
Posts: 1,247
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Quote:
Originally Posted by ajm1571 you should be able to tune 20m on a 40m antenna that is coax fed. Don't quote me on that, but it should work. | Define "work".
You might make the transmitter think it's looking into a good match, but the SWR downstream from the tuner is going to be in the many hundreds, if not thousands, of ohms, and you'll still have a ton of loss in the coax. If the length of the coax isn't too great, this might be acceptable to you. 20:1 is not out of the ballpark for a 40 meter antenna on 20 meters. Figuring a 50 foot length of RG-213, the loss is "only" about 2.6 dB @14 MHz, which is still almost half your power.
Don't forget that you'll have the same losses on receive.
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02-13-2009, 09:19 PM
|  | Senior Member | | Join Date: Apr 2005 Location: Tampa Bay Florida
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Quote:
Originally Posted by Beetle Define "work".
You might make the transmitter think it's looking into a good match, but the SWR downstream from the tuner is going to be in the many hundreds, if not thousands, of ohms, and you'll still have a ton of loss in the coax. If the length of the coax isn't too great, this might be acceptable to you. 20:1 is not out of the ballpark for a 40 meter antenna on 20 meters. Figuring a 50 foot length of RG-213, the loss is "only" about 2.6 dB @14 MHz, which is still almost half your power.
Don't forget that you'll have the same losses on receive. | Will not the using REAL ladder line be minimal compared to coax? |
02-13-2009, 10:11 PM
| | Senior Member | | Join Date: Dec 2005 Location: Western Washington
Posts: 1,247
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Quote:
Originally Posted by Lazybones1222 Will not the using REAL ladder line be minimal compared to coax? | Sure it will, and that's the point. Coax is great feedline IF the feedpoint impedance matches (or approximates) the characteristic impedance of the coax. Typical dipole in free space = 70-75 ohms. Same dipole at realistic height = 50-60 ohms.
Both of these figures are at the frequency at which the dipole is 1/2 wavelength, which we've established as 7 MHz. At 2x that frequency, the feedpoint impedance is going to be very high. Same at 4x, 6x, and other even multiples. At ODD multiples, say 3x (21 MHz; 15 meters), the feedpoint impedance will again be low, and 40 meter, coax-fed dipoles are widely used on 15 meters with good results.
It's interesting to note that even at even multiples of the frequency, with SWR around 20:1, a dipole is still resonant. An antenna analyzer at the feedpoint will confirm that.
A "resonant" antenna doesn't necessarily have a low SWR.
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02-13-2009, 10:46 PM
| | Senior Member | | Join Date: Sep 2006 Location: Fountain, MI
Posts: 100
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Quote:
Originally Posted by Beetle Define "work".
You might make the transmitter think it's looking into a good match, but the SWR downstream from the tuner is going to be in the many hundreds, if not thousands, of ohms, and you'll still have a ton of loss in the coax. If the length of the coax isn't too great, this might be acceptable to you. 20:1 is not out of the ballpark for a 40 meter antenna on 20 meters. Figuring a 50 foot length of RG-213, the loss is "only" about 2.6 dB @14 MHz, which is still almost half your power.
Don't forget that you'll have the same losses on receive. | that answered my question that was within a statement lol
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Allen
CDX015
2RT015
QS015
015 from Michigan
KD8FXB
Kenwood TS430s Maco 3's, A99, 80-10 balanced wire and a 20m vertical dipole
" LIFE'S A B**CH, DEAL WITH IT" |
02-13-2009, 11:18 PM
| | Senior Member | | Join Date: Apr 2002
Posts: 4,745
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Quote:
Mole...just won a Kenwood AT-130 antenna tuner on eBay, it's the matching unit to this TS-130S. I don't believe it has the capacity for a balanced line feed since the description stated that it has 4 SO-239 connectors for 4 different antenna feeds....
Are you telling me that with a coax feed I won't be able to tune a 40m dipole to work on 20m...or any other band......????
That would suck.....
| No, I didn't say that. You should be able to tune it with coax feed line and will also have fun talking too. But (as Beetle described very well) the feed line loss can be significant doing it that way which will severly affect your TX/ RX signal strength. Using ladderline minimizes those losses to next to nothing . It's also so cheap that it really makes it worth considering. There are some issues you have to consider, however. You can't just strap it to the side of your antenna mast like coax. You must figure out a way to make it "stand off" from the mast and also need to run it at 90 degrees when you need to cross other metal surfaces (like rain gutters). If your exterior walls are made of stucco and chicken wire, you really need to get it away from that a bit. Other than those few issues, it's a piece of cake. You say your tuner only has S0-239 connectors? No problem; use a balun. You don't want to deal with the stucco/chicken wire/rain gutter issue? Run a 10' length of coax out of the shack, then attach a balun and run the ladder line the rest of the way.
There are a lot of ways to skin this cat.  |
02-14-2009, 02:35 AM
| | Senior Member | | Join Date: May 2008 Location: 35 miles ESE of Indianapolis
Posts: 141
| | AT-130 tuner
Tony: Are you sure, you purchased the KWD AT-130 tuner?
This tuner has only ONE coax in/out...unless it has been modified.
The tuning range is really pretty slim. This tuner is made to only tune coax antennas with about a 3 or 4 swr or smaller (about 200 Ohm range) nice little unit for mobile/base unit...but for example using a 40m dipole it should be able to tune the entire 40m band... and then tune your 40m antenna on 15 meters. This tuner may not have the range to tune your 40m on 20m...
I was going to email you the manual but did not find your AD on Qrz or here...let me know if you need it and I can send it along...
Glad your enjoying the new rig...have fun...hope to meet you "In the Air"
I'll be on 3865 Sunday morning...if I do not have to work. I run that mobile early in the AM from about 6 Am EST to around 7 AM also...
All the Best
BJ
PS: Look for a Shure 444D or M/desk top... great Mic for that rig. I have also used a Shure S58 and couple other studio mics on them that work well. Never much cared for the factory hand mic but that's me.
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02-14-2009, 05:21 AM
| | Senior Member | | Join Date: Apr 2005 Location: Tampa Bay Florida
Posts: 872
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Quote:
Originally Posted by Lazybones1222 Will not the using REAL ladder line be minimal compared to coax? | 65 feet of wire, some of this ladder line, and a tuner - and you are good to go. This ladder line is the snaizzle. Or just look how he did it and make your own. I will never go back to coax (in most applications).
real ladder line : http://www.w7fg.net/ladder/totower.JPG Ladder line photos & comments |
02-14-2009, 05:54 AM
| | Senior Member | | Join Date: Jun 2008
Posts: 351
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Quote:
Originally Posted by N2ITH |
being "stoked" is one thing,....
being out of band is entirely another matter 
just sayin  | | |
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